On July 4, 1776, the Second Continental Congress, gathered in Philadelphia, to adopt the Declaration of Independence. Two hundred years later, some 20 miles west of Independence Hall, in a nondescript office park near Washington’s Valley Forge headquarters, John C. Bogle and the fledgling Vanguard Group launched the first index mutual fund, a declaration of independence from ruinous investment fees. On August 31, the indexing revolution [marked] its 37th anniversary....